INTRODUCTION Passage of voter-driven marijuana reform laws signals a shift in public attitudes for marijuana use. For providers, legalization may necessitate practice modifications, particularly regarding patient-provider conversations about use and risk. We examined healthcare providers' knowledge of marijuana laws and health implications, professional practice behaviors, and attitudes about training. MATERIALS AND METHODS We surveyed 114 Colorado-based providers who care for children, adolescents, pregnant and breastfeeding women using a Venue-Day-Time survey methodology throughout Colorado. The survey captured providers' (e.g., physicians, nurses, medical assistants) knowledge of state marijuana laws, risk perceptions, counseling practices, and continued training needs. RESULTS Providers were knowledgeable about marijuana laws, cautious supporting legalization, and perceived moderate to high risks, particularly for certain groups. About 50% of providers working with adolescents and pregnant or breastfeeding women assessed marijuana use "every" or "most" visits; 23% of those working with children reported such behavior. Conversations about specific risks varied between groups. Few providers felt completely knowledgeable about marijuana health risks and lacked confidence talking to patients about this issue. CONCLUSIONS Providers frequently assess patients' marijuana use; however, they are uncomfortable and inconsistent talking to patients about specific marijuana health effects. Additional education is warranted, particularly as it relates to talking to patients about the danger of second hand smoke exposure, underage use, safe storage, and the over-consumption of edibles.